Doctors swallowed special pressure catheters and then studied, on each other, the pressure generated in the chest and stomach for all three techniques.

They found equal effectiveness in all three measures.

Professor Sir Malcolm Green said: “People are often embarrassed when they start to choke and move away from their friends to somewhere private, to the toilets or out onto the street, and that can result in their death.

“We need to make sure they stay where they are and know how to do the manoeuvre on themselves or over the chair they have just been sitting on.”